The propeller shaft, or drive shaft, connects a transmission output shaft to a differential shaft of a vehicle. Generally, universal joints are used to connect the propeller shaft to both the transmission output shaft on one end and the differential shaft on the other end. The universal joint should permit articulation to accommodate changes in driving angle (or road incline) between the propeller shaft and the connected output shaft or differential shaft.
Constant velocity joints are universal joints that are able to transfer torque from the transmission output shaft to the differential pinion shaft at generally large driving angles efficiently and smoothly. One type of constant velocity joint includes a tripod outer race; roller bearings; and a tripod inner member. Further, a rubber boot protects the constant velocity joint from exposure to dirt and moisture.
Typically, for use in with the propeller shaft, the constant velocity joint is welded onto the end of a tubular section of the propeller shaft. Therefore, it is desirable that the configuration of the outer race of the constant velocity joint corresponds to the configuration of the tubular section of the propeller shaft to provide an optimal surface area for welding the constant velocity joint to the propeller shaft. FIG. 1 illustrates the present practice of joining a tripod constant velocity joint 100 to a tubular section of a propeller shaft 14. The tripod constant velocity joint 100 is attached to the propeller shaft 14 by welding, as illustrated FIG. 1 by welding bead, W. To have optimal surface area for welding the constant velocity joint 100 to the propeller shaft 14, outer race 110 is generally cylindrical. However, producing the cylindrical tripod outer race 110 is difficult using traditional manufacturing extrusion processes. Specifically, it is difficult to control the width and form of roller tracks of the outer race within the tolerances required for use of the constant velocity joint in a high-speed propeller shaft.
FIG. 2 illustrates the difficulties with trying to attach a typical tripod constant velocity joint outer race 120, produced by the traditional manufacturing extrusion process, to the propeller shaft 14. The constant velocity joint 100 is provided with a tripod outer race 120 that is secured to an end of the propeller shaft 14. As illustrated, gaps exist between the tripod outer race 120 and the propeller shaft 14.